Glow discharge indicator tube



July 12 1966 J. HoRsx-:LING

GLOW DISCHARGE INDICATOR TUBE Filed May 2, 1962 FIGJ IIIII INVENTOR JAN HORSEL ING AGEN United States Patent 27.4,225 Claims. (Cl. S13-109,5)

j Claims V glow discharge indicator tube U mbei 'of cathodefs4 are arranged in the Aform gits br'ch'a'racte's in parallel planes behind one another.

,y viproblein with "glow discharge indicator tubes is that tlreclaracters disposed farther "to the front, mask the characters farther to the rear when the latter are glowing. Particularly 'the-digit 1, the minus sign or another sign of small length` have a strongly masking effect, since the small lengthof the sign requires a width sufficient for taking 'up the same amount Aofcurren't as the larger charaetejrs.

.j The fmasking problem is even more conspicuous in biquinary tubes, since in these tubes the odd-numbered digits are preferably farrangedin the front part of the tube and, moreover, a partition is arrangedbetween the oddnumbered digits and the 'even-"numbered digits. If the dfi-gitl does `not possess an .adequate surface, anomalous yb'lrli'ng'b"`cc11'r`s,"in addition, so that'the 'coupled digit tends to burn simultaneously, which is undesirable.

A principal object of my invention is to provide a new and novel glow-discharge indicator tube in which the visibility of the character-electrodes, especially those farther to the rear, is improved.

Another object of my invention is to provide a new and novel glow-discharge indicator tube in which the smaller character-electrodes do not mask the larger character electrodes.

These and further objects of my invention will appear as the specification progresses.

In a glow discharge indicator tube a sign of small length consists, in accordance with my invention, of two identical cathodes arranged at a short distance one behind the other, each parthaving the same width as or a smaller width 4than that of the longer characters.

'Ilhe structure described above provides twice the available cathode length, while in the narrow space between the two cathode parts, to a certain extent, a hollowcathode effect may occur, so that an even higher current may be taken without the risk of anomalous burning. The distance between the two parts of the character need only be a few tenths of a millimeter, so that the depth of the stack of characters is hardly affected. Even if no hollow-cathode eifect occurs, the cathode glows of the two cathode parts are observed as being integral with each other.

The invention will now be described more fully with reference to the accompanying drawing, in which FIG. 1 is a perspective View showing a biquinary glow-discharge indicator tube according to the invention;

FIG. 2 is a longitudinal sectional view illustrating the relative arrangement of a few parts of the tube; and

FIG. 3 is a sectional view of a connecting wire and a contact pin.

Referring to FIG. 1, the character-electrodes are enclosed in a circular-cylindrical envelope 1 of clear glass, having a bottom 2 provided with a plurality of contact pins 4 and an upper side 3. The electrodes are disposed between two insulating plates 5 and 6, preferably of mica, the latter being provided with resilient teeth. The mica plates have a diametrical slot 7 and 8, respectively, to allow the supply wires and connecting wires to pass, which 3,260,882 Patented July 12, 1966 slots divided the mica plates almost into two pieces. The foremost anode 9 consists of guaze, having narrow beams on the upper side and on the bottom side. The side wings reach into the plane of the dig-it nearest the partition. The rear anode 10 consists of iron with an aluminium coating, having a dull surface so that reflections are minimized. Molybdenum partition 11 is arranged in front of the axis of the tube and is formed by lower and upper beams 12 and 13, respectively, and side beams 14, on which vtungsten wires 15 are wound, which wires have a thickness lof 10p and a pitch of 50u. Enamelled pins '16 extend through the upper and the lower sides of the two anodes, the ends of which are provided with flattened caps 17, which are insulated 'from the anodes by mica plates 18. yOnto the pins 16 are strung the cathode digits, having a thickness of 0.15 mm. and insulated from each other by glass beads 19 of a thickness of 0.6 mm. On each side of the partition the digits are insulated by two similar beads 19. The contact pins 4 of the tube bottom are partly connected directly to the anodes and the partition and, moreover by iiexible supply wires 20 to digits of the two groups, so 'that only one digit of each pair is connected to a pin. 'Ilhrough the slot 8 in the topmost mica plate extend connecting wires 21, which connect the digits of a pair with each other. The connecting wires V21, the supply wires 20 and the uncovered vparts of the supply .pins 4 are coated with a graphite layer 22, which prevents the wires and the pins from glowing together with the digits.

Beneath the mica plate 5 is disposed a small, sealed glass tube 24, lled with a quantity of mercury 25 and surrounded by a filament wire 26. At a suitable time dur- 4ing the manufacture of the tube the mercury is released by heating the wire 26. The tube is iilled with neon and an addition of 0.25% of argon, at a pressure of mms. Hg.

The ratio between the minimum covering current and the current at which simultaneous burning of the coupled digit occurs is a factor 2 to 3.

The bulb is coated with a red lacquer layer 27 to minimize the blue haze of the cathode glow.

IFIG. 2 illustrates how the digit 1, lying completely in the foreground, is formed by two parts 24 and 25 sepanated by mica plates 23 of a thickness of 0.2 mm., said parts both participating in the discharge.

IFIG. 3 shows the graphite layer 22 covering the section of the connecting wire 21 and the section of the pin 4.

The construction of the tube and the graphite layer are the subject matter of copending, concurrently filed patent applications, Serial Nos. 191,874 and 191,824, now abandoned.

While I have described my invention in connection with a specic embodiment, other modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention which is dened in the appended claims.

What I claim is:

A1. A glow-discharge indicator tube comprising an envelope containing an ionizable gaseous medium, and a plurality of character-like electrodes arranged in parallel planes one behind the other, a character-electrode of smaller length than the other character electrodes comprising two like portions spaced a relatively short distance one behind the other, and having a width not greater than that of the other character electrodes.

2. A glow-discharge indicator tube comprising an envelope containing an ionizable gaseous medium, a plurality of character-like electrodes arranged in parallel planes one behind the other, a character-electrode of smaller length than the other character electrodes comprising two :like portions spaced a relatively short distance one behind the other, and having a width not greater than that of the other character electrodes, and a supply of mercury within said envelope for reducing sputtering of the characterlike electrodes and increasing the life of the tube.

3. A glow-discharge indicator tube comprising an envelope containing an ionizable gaseous medium, and a plurality of character-like electrodes arranged in parallel planes one behind the other, a character-electrode of smaller length than the other character electrodes comprising two like portions spaced a distance one behind the other/ at which a hollow cathode effect is obtained when said portions are glowing, and having a width not greater than that of the other character electrodes.

4. A glow-discharge indicator tube comprising an envelope containing an ionizable gaseous medium, a pluralityof character-like electrodes arranged in parallel planes one behind the other, a character-electrode of smaller length than the other character electrodes comprising two like portions spaced a relatively short distance one behind the other, and having a width not greater than that of the other character electrodes, and a red transparent coating on the outer surface of said envelope for minimizing the blue haze of cathode glow.

5. A glow-discharge indicator tube comprising an envelope containing an ionizable gaseous medium, a plurality of character-like electrodes arranged in parallel planes one behind the other, a character-electrode of smaller length than the other character electrodes comprising two like portions spaced a distance one behind the other at which a hollow cathode eiect is obtained when said character electrodes are glowing, and having a width not greater than that of the other charac/ter electrodes, a supply of mercury within said envelope for reducing sput-y tering from the character-like electrodes and increasing the life of the tube, and a red transparent outer coating on said envelope for minimizing the blue haze of cathode glow.

6. A glow-discharge -indicator tube comprising an envelope containing an ionizable gaseous medium, -at least two rod-like support members disposed in spaced relation within the envelope, a plurality of character-like electrodes supported by said support members in parallel planes one behind the other, insulating spacer members interposed between successive character electrodes on said support member serving to space the character electrodes and insulate one from the other, one of said character electrodes being of smaller length than the other character electrodes and comprising two like portions spaced a relativelyvshortl said latter electrode having` distance one behind the other, a width not greater than any other character electrode,

and lead-in mem-'bers connected to each of the character' electrodes `and extending outside the region between the.

supporting members.

References Cited by the Examiner UNITED STATES PATENTS 2,796,557 7/1957 Geisler 313-204 2,991,387 7/1961 McCauley 313-1095 2,996,635 S/1961 Klepp et al. 3l3-109.5

GEORGE N. WESTBY, Primary Examiner.

DAVID I. GALVIN, Examiner.

A. J. JAMES, C. R. CAMPBELL, Assistant Examiners.'- 

1. A GLOW-DISCHARGE INDICATOR TUBE COMPRISING AN ENVELOPE CONTAINING AN IONIZABLE GASEOUS MEDIUM, AND A PLURALITY OF CHARACTER-LIKE ELECTRODES ARRANGED IN PARALLEL PLANES ONE BEHIND THE OTHER, A CHARACTER-ELECTRODE OF SMALLER LENGTH THAN THE OTHER CHARACTER ELECTRODES COMPRISING TWO LIKE PORTIONS SPACED A RELATIVELY SHORT DISTANCE ONE BEHIND THE OTHER, AND HAVING A WIDTH NOT GREATER THAN THAT OF THE OTHER CHARACTER ELECTRODES. 